llvm dev - Jan 2010 - [LLVMdev] Deterministic iteration over llvm iterators

Forgot cc, the entire group.

How can deterministically iterate over the uses of a variable. i.e. the uses
should be any particular order that doesn't change from execution to
execution of the opt tool.

To make myself more clearer, here is a snippet of code that has Values
reordered each time I analyze a particular piece of code(which doesn't
change) with the LLVM opt tool and my LLVM pass.


void Anders::id_gep_ce(Value *G){
  assert(G);
  //Check all GEP and bitcast ConstantExpr's using G.
  for(Value::use_iterator it= G->use_begin(), ie= G->use_end(); it != ie;
++it){
    ConstantExpr *E= dyn_cast<ConstantExpr>(*it);
    do_something_with(E);
}


i.e. use_begin() and use_end() still works correctly such that iterates
through all the uses of G but the uses themselves are reordered. My question
is whether I can deterministically iterate through all the uses of G each
time run the analysis.

Currently this is what happens in principle:

Execution 1: <val 1> <val 2> <val 3>

Execution 2: <val 2> <val 1> <val 3>

The llvm version that I am using llvm 2.5. My machine is an x86 32 bit dual
core machine.

The code that I am analyzing is some bytecode that is generated apriori.
This is only generated once, and the analysis reads this particular bytecode
file to perform an analysis using the opt tool.

Thanks,
Augustine
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On Jan 26, 2010, at 7:23 AM, Augustine Mathews wrote:
> Forgot cc, the entire group.
>
> How can deterministically iterate over the uses of a variable. i.e.  
> the uses should be any particular order that doesn't change from  
> execution to execution of the opt tool.
>
> To make myself more clearer, here is a snippet of code that has  
> Values reordered each time I analyze a particular piece of  
> code(which doesn't change) with the LLVM opt tool and my LLVM pass.
use_iterator should be deterministic.
> Currently this is what happens in principle:
>
> Execution 1: <val 1> <val 2> <val 3>
>
> Execution 2: <val 2> <val 1> <val 3>
>
> The llvm version that I am using llvm 2.5. My machine is an x86 32  
> bit dual core machine.
This was a bug in the LLVM 2.5 bitcode reader which has already been  
fixed, please update to mainline.

-Chris

There is a problem in this area (pr5680).  The use order is kept consistent in
memory, but writing the IR to a bitcode file causes the order to be lost.

http://llvm.org/bugs/show_bug.cgi?id=5680

On Jan 26, 2010, at 7:23 AM, Augustine Mathews wrote:
> Forgot cc, the entire group.
> 
> How can deterministically iterate over the uses of a variable. i.e. the
uses should be any particular order that doesn't change from execution to
execution of the opt tool.
> 
> To make myself more clearer, here is a snippet of code that has Values
reordered each time I analyze a particular piece of code(which doesn't
change) with the LLVM opt tool and my LLVM pass.
> 
> 
> void Anders::id_gep_ce(Value *G){
>   assert(G);
>   //Check all GEP and bitcast ConstantExpr's using G.
>   for(Value::use_iterator it= G->use_begin(), ie= G->use_end(); it !=
ie; ++it){
>     ConstantExpr *E= dyn_cast<ConstantExpr>(*it);
>     do_something_with(E);
> }
> 
> 
> i.e. use_begin() and use_end() still works correctly such that iterates
through all the uses of G but the uses themselves are reordered. My question is
whether I can deterministically iterate through all the uses of G each time run
the analysis.
> 
> Currently this is what happens in principle: 
> 
> Execution 1: <val 1> <val 2> <val 3>
> 
> Execution 2: <val 2> <val 1> <val 3>
> 
> The llvm version that I am using llvm 2.5. My machine is an x86 32 bit dual
core machine.
> 
> The code that I am analyzing is some bytecode that is generated apriori.
This is only generated once, and the analysis reads this particular bytecode
file to perform an analysis using the opt tool.
> 
> Thanks,
> Augustine
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

I mean SVN head, but it might have been fixed in 2.6 as well, I don't  
remember.

On Jan 25, 2010, at 2:47 PM, Augustine Mathews wrote:
> Thanks chris.
>
> Do you mean llvm 2.6 when you say mainline or something else?
>
> Augustine
>
> On Mon, Jan 25, 2010 at 4:27 PM, Chris Lattner <clattner at
apple.com>
> wrote:
>
> On Jan 26, 2010, at 7:23 AM, Augustine Mathews wrote:
>
> Forgot cc, the entire group.
>
> How can deterministically iterate over the uses of a variable. i.e.  
> the uses should be any particular order that doesn't change from  
> execution to execution of the opt tool.
>
> To make myself more clearer, here is a snippet of code that has  
> Values reordered each time I analyze a particular piece of  
> code(which doesn't change) with the LLVM opt tool and my LLVM pass.
>
> use_iterator should be deterministic.
>
>
> Currently this is what happens in principle:
>
> Execution 1: <val 1> <val 2> <val 3>
>
> Execution 2: <val 2> <val 1> <val 3>
>
> The llvm version that I am using llvm 2.5. My machine is an x86 32  
> bit dual core machine.
>
> This was a bug in the LLVM 2.5 bitcode reader which has already been  
> fixed, please update to mainline.
>
> -Chris
>
>
>
>
> -- 
> Augustine Mathew
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